class_docstr: Stores/loads data to increase performance.
  
  :param cache_db: specific DB for specific data
code: def __len__(self):
      return len(self._db)
  
file_path: FEDOT/fedot/core/caching/base_cache.py
imports: from typing import Union
  from golem.core.log import default_log
  from golem.utilities.singleton_meta import SingletonMeta
  from fedot.core.caching.pipelines_cache_db import OperationsCacheDB
  from fedot.core.caching.preprocessing_cache_db import PreprocessingCacheDB
label_desc: Use image node_id 4 for calling the BaseCache obj's underlying member method code with example usage: obj.__len__() and returns: len